This proposal is for continuation of research in the natural history, epidemiology, statistical conduct, design, collation and treatment of childhood malignant disease in a sophisticated multimodal manner. This institution has been a member of the Children's Cancer Study Group since 1959. Over the past 18 years a very strong referral pattern for children with malignant disease has been established throughout the Pacific Northwest. From October 1, 1976 through August 31, 1977 a total of 138 children were seen with childhood malignancies: 64 with leukemia and 74 with solid tumors. This institution had the second highest entry in protocol studies of the Children's Cancer Study Group during the above period. In addition to the Children's Cancer Study Group program we are continuing our collaboration with Dr. E. Donnal Thomas in bone marrow transplantation. Twelve bone marrow transplantations were performed at this institution during the above time period. Also continuing is Dr. I. Bernstein's work in tumor immunology with Drs. K. and I. Hellstrom and Dr. W.A. Bleyer's work with the National Cancer Institute in high-dose methotrexate pharmacology studies and intraventricular methotrexate via the Ommaya reservoir. This program continues as the Pediatric Oncology Unit of the Fred Hutchinson Cancer Research Center.